Myocardial protection by retrograde cardioplegic perfusion through the right atrium

Three types of cardioplegic delivery with ink into the isolated canine hearts were compared: (1) antegrade aortic root perfusion (AARP), (2) retrograde coronary sinus perfusion (RCSP) and (3) retrograde right atrium perfusion (RRAP). Ink was not distributed in the area distal to the coronary occlusion by AARP but well distribution in the same area by RCSP or RRAP. The right ventricular wall and ventricular septum were poorly perfused by RCSP but well perfused by RRAP. During cardiopulmonary bypass, RRAP created a fairly rapid cardiac arrest and satisfactory myocardial cooling. During Perfusion, the right heart was somewhat dilated but all the 10 canine hearts rebeat well. The left and right ventricular ejection fraction showed no significant change after bypass. No marked myocardial ultrastructural injury was found in left and right ventricles at the end of 90 minutes' ischemia. 4 patient, 1 of whom had 162 minutes' aortic cross-clamping received RRAP in operations on ascending aorta or coronary arteries and the myocardial protect ion was satisfactory. No complication was found pertaining to RRAP.     

Aortic valve replacement. Aortic root versus coronary sinus perfusion with blood cardioplegic solution.

The role of retrograde coronary sinus cardioplegia in patients undergoing aortic valve replacement for aortic stenosis alone or in combination with myocardial revascularization has not been fully defined. Sixty-three patients undergoing elective aortic valve replacement received cold potassium blood cardioplegic solution via either the aortic root (36 patients) or the coronary sinus (27 patients). The patients were similar with respect to age, degree of aortic stenosis, ventricular function, severity of coronary artery disease, crossclamp time, completeness of revascularization, and mean volume and temperature of the infusion solution. The mean septal temperature and the release of myocardium-specific isoenzyme in the first 2 hours after crossclamp removal was higher in the retrograde group (p less than 0.008). Right and left ventricular function was preserved equally in the two groups, and volume-loading studies suggested improved diastolic performance in patients having retrograde cardioplegia. There were no differences between the two groups with respect to clinical outcome. We conclude that coronary sinus cardioplegia is as safe as aortic root perfusion for myocardial preservation in patients undergoing elective aortic valve replacement.     

Reducing intraoperative myocardial acidosis by continuous cardioplegic perfusion via the coronary sinus

Continuous retrograde coronary sinus perfusion (RCSP) can deliver cardioplegic solution homogeneously to the myocardium via the disease-free venous system. However, administration of cardioplegic solution through the coronary venous system necessitates low pressure infusion which may limit the rate of cardioplegic delivery. In addition, infusion of the solution at low flow rates may not prevent the development of myocardial acidosis during arrest. To determine if RCSP is capable of limiting intraoperative myocardial acidosis, open-chest pigs, monitored by intramyocardial pH probes, underwent cardioplegic arrest with a single dose aortic root infusion followed by a 45-min period of no RCSP (Group 1), RCSP of 25 mEq/liter bicarbonate-buffered cardioplegic solution (Group 2), RCSP of blood-buffered cardioplegic solution (Group 3), and RCSP of histidine-buffered cardioplegic solution (Group 4). There were no significant differences between the groups with respect to baseline pH, with a range of 7.27 to 7.32. At the end of the 45-min arrest period, Group 2 had a statistically higher pH, 7.06 +/- 0.08, compared to Group 1, 6.74 +/- 0.08 (P less than 0.05). Hearts in Groups 3 and 4 demonstrated preservation of preischemic pH levels after 45 min of arrest, 7.29 +/- 0.07 and 7.37 +/- 0.10, respectively, significantly higher than either Group 1 or 2 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Myocardial protection by retrograde cardioplegia in arterial switch operation

Retrograde coronary sinus perfusion of cold cardioplegic solution was evaluated in infants undergoing an arterial switch operation for transposition of the great arteries. To assess myocardial injury during ischemia, hemodynamic measurements were conducted at weaning from cardiopulmonary bypass and a postoperative assay of creatine kinase isoenzyme MB was performed. In 22 infants with retrograde coronary sinus perfusion, the initial cardioplegic infusion was performed through the aortic root and additional infusion was repeated every 30 minutes by retrograde coronary sinus perfusion. The other 11 infants received additional solution by antegrade selective coronary artery perfusion. The aortic cross-clamp time in the retrograde coronary sinus perfusion group was significantly shorter than that in the antegrade selective coronary perfusion group (128 +/- 19 versus 143 +/- 21 minutes, p less than 0.05). There were no significant differences between the two groups in terms of postoperative hemodynamic variables and enzyme indexes. Eight neonates in the retrograde coronary sinus perfusion group also exhibited enzymatic and hemodynamic indexes similar to those of older infants. These results suggested that retroperfusion of cardioplegic solution was a safe and useful means of myocardial protection in infants and neonates because of the simplification of the operative procedure and the avoidance of traumatic injury to the coronary ostia.     

Warm retrograde cardioplegia. Protection of the right ventricle in mitral valve operations.

Hypothermia is believed to be the most important aspect of successful myocardial protection with retrograde coronary sinus cardioplegia. Because nutritive capillary flow to the right ventricle and septum is thought to be diminished with retrograde perfusion, these areas of the myocardium are considered at higher risk for intraoperative deterioration without the added protection of hypothermia. Recently we introduced warm aerobic arrest as an alternative to conventional methods of myocardial protection. We present our clinical results in 37 patients with mitral valve disease (+/- aortic valve, aortic root, or coronary artery disease) who underwent various cardiac procedures for which warm blood cardioplegic solution was delivered continuously via the coronary sinus after antegrade arrest. Thirty-five of the patients were in New York Heart Association class III or IV, and 19 patients had grade 3 or grade 4 left ventricular function. Sixteen patients had pulmonary hypertension, three with suprasystemic pressures, and marked right ventricular hypertrophy. Two patients had associated left ventricular hypertrophy. Nearly all patients returned to normal sinus rhythm shortly after removal of the aortic crossclamp, and they were easily discontinued from cardiopulmonary bypass even with crossclamp times of 3 hours. The 30-day hospital mortality rate was 2.7%. The perioperative myocardial infarction rate was 5.4%, and the prevalence of low-output syndrome was 10.8%. The results suggest that retrograde coronary sinus perfusion of blood cardioplegic solution at 37 degrees C is an effective method of myocardial protection even in patients with pulmonary hypertension at high risk for right ventricular failure. Its efficacy in this circumstance does not reside in its ability to deliver hypothermia.     

Is cold, cardioplegic solution harmful to the lungs?

The effects of pulmonary flush with cold cardioplegic solution were investigated in 55 patients undergoing coronary artery bypass grafting. Extracorporeal circulation with bicaval cannulation was used in all cases, and single-dose cardioplegic solution was injected into the aortic root. In one of two randomly selected groups (n = 27) the cardioplegic solution was allowed to pass through the lungs and then evacuated via a left ventricular vent. In a second group (n = 28) the vent was first temporarily placed in the right atrium for evacuation of the cardioplegic solution, and the aortic root was vented later. Hemodynamic, metabolic, hematologic and radiographic changes were studied during the early postoperative period. No harmful effects of the pulmonary passage could be demonstrated. On the contrary, a protective effect was indicated, as the pulmonary vascular resistance index was reduced immediately and for 2 hours postoperatively. The ratio of left ventricular to right ventricular stroke work in the early postoperative period gave the same indication.     

Retrograde coronary sinus perfusion of cardioplegic solution in Jatene operation in neonates and infants

The clinical benefits of retrograde coronary sinus perfusion of a cardioplegic solution were investigated in 7 neonates and 23 infants undergoing Jatene operation. After an initial infusion of albumin-containing crystalloid cardioplegic solution via the aortic root, 21 patients received additional solution delivered by retrograde coronary sinus perfusion (retrograde group) and 9 patients received by selective antegrade coronary perfusion (antegrade group) every 20 to 30 minutes. There were no differences in age, weight, and left ventricular preoperative pressure and morphology between the two groups. Aortic cross-clamping time was 130 +/- 18 minutes in retrograde group and 147 +/- 20 minutes in antegrade group. Postoperative assays of CPK-MB, GOT and LDH, and hemodynamic measurements immediately after cessation of cardiopulmonary bypass (CPB) were carried out in all patients. Although there was no significant difference between the two groups in terms of enzyme indexes, retrograde group showed a greater variation of sigma CPK-MB from patient to patient than antegrade group. However, hemodynamic parameters of CVP, left atrial pressure and rate-pressure product at 20-30 minutes after CPB were similar in the two groups. Six neonates in retrograde group also demonstrated the similar enzyme indexes and hemodynamic state immediately after CPB to other older patients. We concluded, therefore, that retroperfusion of cardioplegic solution in neonates and infants provides satisfactory myocardial protection as well as antegrade perfusion, and it was a useful means of cardioplegic delivery in Jatene operation, because of its simplicity.     

Coronary sinus versus aortic root perfusion with blood cardioplegia in elective myocardial revascularization

The role of retrograde coronary sinus cardioplegia in patients undergoing elective coronary artery bypass grafting has not been fully defined. Forty patients undergoing coronary artery bypass grafting received either aortic root (20 patients) or coronary sinus (20 patients) cold potassium blood cardioplegia. The patients were similar with respect to age, ventricular function, severity of coronary artery disease, cross-clamp time, completeness of revascularization, frequency of internal mammary artery grafting, and mean infusate volume and temperature. The time required to deliver the initial dose of cardioplegic solution and the time to achieve arrest were prolonged in the coronary sinus group (p less than 0.001 and p less than 0.02, respectively). There were no differences between the two groups postoperatively with regard to enzymatic indices, hemodynamic measurement, or clinical outcome. Right ventricular function was preserved equally in both groups. We conclude that coronary sinus cardioplegia is a safe alternative to aortic root perfusion, but offers no advantage in elective myocardial revascularization.     

Optimal delivery of cardioplegic solution for "redo" operations.

Increasing experience suggests that retrograde cardioplegia offers several benefits during cardiac reoperations. However, the need for dissection to allow caval snares for open coronary sinus intubation or to palpate the atrioventricular groove for transatrial coronary sinus intubation may disturb diseased vein grafts or require more dissection than necessary. Although antegrade-retrograde techniques can be used, antegrade cardioplegia risks atheromatous embolization from old vein grafts. To optimize delivery of cardioplegic solution, we designed and used "no touch" transatrial intubation of the coronary sinus for retrograde delivery of cardioplegic solution in 63 consecutive patients aged 20 to 87 years (mean 68 years) undergoing 36 redo coronary bypass operations, 7 combined redo coronary bypass/valve replacements, 6 redo aortic valve repairs/replacements, 6 redo mitral valve repairs/replacements, 4 redo double valve repairs/replacements, 2 redo triple valve repairs/replacements, and 2 redo composite aortic valve and arch replacements. "No touch" coronary sinus cannulation was achieved by minimally dissecting the aorta and high right atrium enough for two purse-string sutures. No attempt was made to dissect the junction of the inferior vena cava and atrioventricular groove if old vein grafts were present. The distal pressure line of the Gundry DLP RCSP retrograde cardioplegia cannula (DPL, Inc., Grand Rapids, Mich.) was connected to a transducer, flushed, and then introduced into the right atrium. The pressure tracing thus obtained was observed while the catheter was advanced, using its curved stylet, "blindly" without touching the heart, through the right atrium into the coronary sinus until a coronary sinus waveform was obtained (similar to floating a thermodilution catheter). The catheter's distal balloon was then inflated to occlude the coronary sinus momentarily. A rise in sinus pressure confirmed placement. If pressure did not rise, the cannula was usually in the right ventricle and was repositioned. All coronary sinuses were successfully intubated blindly. Bypass was then instituted, the aorta crossclamped, and the proximal aorta vented. Old vein grafts were cut at the aorta before retrograde cardioplegia was begun; atheromatous material was routinely flushed retrogradely from vein grafts. Only after arrest were hearts dissected as needed. Antegrade cardioplegia was not used. There were two (3%) deaths, both from hospital-acquired pneumonia, no perioperative myocardial infarctions, and no episodes of heart block. Inotropic agents were used in six of 63 patients (10%). We conclude that "no touch" transatrial retrograde cardioplegia offers optimal, simplified myocardial protection for cardiac reoperations, permits arrest of the heart before cardiac manipulations, and expands the use of retrograde cardioplegia by obviating cardiac dissection.     

Perioperative myocardial protection with the calcium antagonist diltiazem.

The effect of the calcium channel blocker, diltiazem, on cardiac performance was examined in 90 patients who underwent isolated aortic valve replacement for aortic valve diseases with marked left ventricular hypertrophy. The patients were randomly assigned to one of five groups dependent on the treatment plan with diltiazem: group 1, 5-day preoperative treatment with oral administration of 60 mg diltiazem 3 times daily, 10 mg diltiazem intravenously as a bolus dose before the beginning of the cardiopulmonary bypass, and 5 mg diltiazem intravenously 10 min before removal of aortic clamp; group 2, 5-day preoperative treatment with oral administration of 60 mg diltiazem 3 times daily; group 3, 10 mg diltiazem intravenously as a bolus dose before the beginning of CPB and 5 mg 10 min before removal of the aortic clamp; group 4, 15 mg diltiazem in 1000 ml cardioplegic solution, given as additive; group 5, control group not receiving diltiazem. All operative procedures were performed in an identical manner with an average cross-clamping time of 57.7 min and cooling the heart down to 16 degrees-17 degrees septal temperature by perfusion of the coronary arteries with 4 degrees C cold cardioplegic solution. In each patient the heart rate (HR), cardiac output and cardiac index (CO, CI), stroke volume index (SVI), left ventricular stroke work index (LVSWI) and systemic vascular resistance index (SVRI) were recorded and calculated before and after the ischemic period. Transmural samples were obtained three times by needle biopsy technique from the anterior free wall of the heart. Analysis of the variables revealed that: (1) complete cessation of electromechanical activity was achieved significantly more rapidly in groups 1 and 3 than in the other groups; (2) recovery of sinus rhythm and function of the conductive system required significantly longer in groups 1 and 3; (3) the time-related values of the important hemodynamic factors (CO, CI, LWSVI and SVRI) showed a significantly more effective postperfusion cardiac performance in groups 1 and 3 than in groups 2, 4 and 5. An oral dose of 180 mg diltiazem for 5 to 7 days preoperatively in combination with intravenous administration of 10 mg before the beginning of CPB and 5-10 mg during reperfusion can be recommended in patients undergoing open-heart surgery for isolated aortic valve diseases and left ventricular hypertrophy.     

双瓣膜置换患者围术期心排血量与呼出气二氧化碳的关系

目的 探讨双瓣膜置换术患者围术期心排血量监测,提高手术安全性和预测患者预后,及时调整治疗方案。方法 根据Ｆｉｃｋ原理将呼出气二氧化碳（ＥＴＣＯ２）监测用于估计患者围术期心排血量（ＣＯ）,并与有创性温度稀释法进行比较。将１９９１年１０月以来随机选择２０例双瓣膜置换患者分为两组,对照组：使用常规心肌保护液;用药组：常规心肌保护液中加入山莨菪碱,３０ｍｇ／Ｌ。常规体外循环,冠状窦逆行灌液,分别于麻醉前、     

The use of combined antegrade-retrograde infusion of blood cardioplegic solution in pediatric patients undergoing heart operations.

The benefits of combined antegrade-retrograde infusion of blood cardioplegic solution are becoming well known in adult coronary and valvular heart operations. Many of these advantages relate directly to the pediatric patient. They include prompt arrest and even distribution, particularly with aortic insufficiency or open aortic root, avoiding or limiting ostial cannulation, allowing uninterrupted surgical procedures, and flushing air/debris from the coronary arteries. We therefore report on the first 123 pediatric patients at the University of California, Los Angeles, to receive myocardial protection with antegrade (aortic) infusion in conjunction with retrograde (coronary sinus) infusion of blood cardioplegic solution. We employed a retroplegia catheter with a self-inflating and deflating occlusion balloon on the tip of a pressure-monitored infusion cannula that remains in the coronary sinus during the operation. Induction blood cardioplegic solution, 30 ml/kg in equally divided doses, is administered in the coronary sinus first antegrade at an aortic pressure less than 80 mm Hg, followed by retrograde infusion at less than 40 mm Hg. Maintenance cardioplegic solution (15 ml/kg) is administered every 20 minutes through one or both of the infusion cannulas, depending on the surgical procedure. Patients' ages ranged from 1 week to 16 years with a mean of 4.6 years. The following procedures were included in descending order: Fontan 20, atrioventricular valve repair/replacement (and complete atrioventricular canal) 16, aortic root/Konno/Ross 16, Rastelli 13, aortic valve repair/replacement 13, ventricular septal defect (and double-outlet right ventricle) 13, tetralogy of Fallot 10, coronary artery reimplantation/fistula repair 6, truncus arteriosus 4, arterial switch 3, bidirectional Glenn 2, sinus venosus 2, and aortopulmonary window, Senning, Stansel, interrupted aortic arch, and Ebstein's, 1 each. Aortic crossclamp times ranged from 6 to 219 minutes with a mean of 87 minutes. Myocardial oxygen consumption data for a series of six patients indicated the supplemental benefit for retrograde infusion of cardioplegic solution along with antegrade infusion, particularly in hypertrophied myocardium. Three deaths occurred (2.4% 30-day mortality), in the following patients: the first with truncus arteriosus and interrupted aortic arch, the second with complete atrioventricular canal and pulmonary hypertension, and the third with truncal valve regurgitation and replacement. There were no complications related to the retroplegia catheter. From this initial positive experience, we conclude that (1) combined antegrade-retrograde infusion of blood cardioplegic solution can be safely used in an expanding number of pediatric heart operations in all age groups, and (2) combined antegrade-retrograde infusion of blood cardioplegic solution may provide additional myocardial protection, with excellent surgical outcome, in complex congenital heart repairs.     

The Safety of Simultaneous Arterial and Coronary Sinus Perfusion: Experimental Background and Initial Clinical Results

Concern over myocardial damage from simultaneous arterial (antegrade) and coronary sinus (retrograde) perfusion has led to alternating between these delivery routes to maximize their individual benefits. Based upon predominant retrograde drainage via Thebesian veins, this study: (1) confirms experimentally the safety of simultaneous arterial and coronary sinus perfusion; and (2) reports initial clinical application of this combined strategy in 155 consecutive patients. Experimental: Five mini-pigs (25 to 30 kg) underwent 1 hour of aortic clamping with simultaneous aortic and coronary sinus perfusion at 200 mUmin with normal blood (37°C) before and after 30 minutes of perfusion with either warm (37°C) or cold (4°C) blood cardioplegia. Coronary sinus pressure was always less than 30 mmHg. There was no right or left ventricular edema, lactate production, or lipid peroxidation as transmyocardial and myocardial conjugated dienes were unaltered, and postbypass recovered left ventricular end-systolic elastance (conductance catheter) and preload recruitable stroke work Index 101%± 3% and 109%± 90%, respectively. Clinical: Simultaneous arteriaVcoronary sinus perfusion was used in 155 consecutive high risk patients (New York Heart Association Class III to IV) undergoing isolated coronary artery bypass grafting (CABG) (n = 109) and CABG + valve replacementlrepair or aneurysm (n = 46). Included were 16 patients in cardiogenic shock and 24 undergoing reoperation. Mean aortic clamping time averaged 90 ± 4 minutes (range 30 to 207), with 3.5 ± 0.1 grafts per patient; all anastomoses were performed with the aorta clamped. Cold intermittent blood cardioplegia was used for distal anastomoses and valve implantationhepair in 123 patients, and warm continuous blood cardioplegia was used in 32 patients. Following a warm cardioplegic reperfusate, all patients received warm non-cardioplegic blood perfusion simultaneously via grafts and coronary sinus. Coronary sinus pressure was always less than 40 mmHg. Of 18 patients requiring postoperative mechanical circulatory support (IABP), 16 had IABP placed preoperatively for cardiogenic shock. There were three postoperative myocardial infarctions (2%), and six patients died (3.9% mortality). Conclusion: These experimental and clinical findings overcome perceived concerns about myocardial damage from simultaneous arterial and coronary sinus perfusion, and suggest this approach may add to the armamentarium of cardioprotective strategies. (J Card Surg 1994;9:15–25)     

Retrograde coronary sinus cardioplegia for aortic valve operations: a clinical report on 500 patients

Retrograde delivery of cardioplegic solutions has recently been the subject of renewed interest, but the reliability of this technique has not been assessed in large clinical series. From 1980 to 1989, we used retrograde coronary sinus perfusion as the exclusive means of cardioplegia delivery in 500 consecutive patients undergoing aortic valve replacement, either isolated (359 patients) or combined with another valve or coronary procedure (141 patients). The coronary sinus was always cannulated under direct vision after bicaval cannulation with snaring. Cold crystalloid cardioplegia was delivered retrogradely at an average flow rate of 100 mL/min in conjunction with topical and systemic (25 degrees C) hypothermia. The mean cross-clamp time was 83 +/- 23 minutes (+/- the standard deviation). There were 31 hospital deaths (6.2%), 20 of which were cardiac related. Transient hemodynamic instability (defined as a need for inotropic agents for less than 24 hours postoperatively) occurred in 16 patients (3.2%), whereas a true low-output syndrome developed in 60 patients (12%). The incidence of clinically significant supraventricular arrhythmias and of permanent conduction defects was 7.4% and 1.2%, respectively. There were three nonfatal coronary venous injuries during our early experience. We conclude that coronary sinus perfusion is a safe and effective means of delivering cardioplegia in aortic valve operations. While providing a degree of myocardial protection similar to that reported with anterograde cardioplegia, the coronary sinus technique offers distinct advantages, in particular, the avoidance of perfusion-related coronary artery complications and the opportunity to repeat cardioplegia administration without interrupting the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Retrograde coronary sinus perfusion

"Redo" operations for coronary artery disease have become commonplace. One of the major complications that occurs is perioperative infarction due to embolization of atheromatous material from diseased veins into the distal coronary arteries. Because of this, we began using retrograde coronary sinus perfusion (RCSP) for delivery of cardioplegia to prevent the embolization of grumous material. It is our belief that retrograde flow through the coronary arteries is an effective preventive measure. In addition, RCSP is a simple method of delivery in redo operations such as aortic valve replacement where the majority of coronary flow is through patent vein grafts. Sixty-five of approximately 3,100 patients in our practice in the past three years underwent a cardiac operation in which RCSP was used for cardioplegia delivery. Ventricular function in all patients was well preserved, and all survived. There were no complications associated with the use of this method.     

Myocardial distribution of retrograde flow through the coronary sinus of the excised normal canine heart

Myocardial distribution of the retrograde flow through the coronary sinus in the canine heart was evaluated by observing the corrosion casts of the myocardial vessels after coronary sinus injection of a low-viscosity resin, Mercox, a compound that passes through capillaries. The apex and the left ventricular free wall were well perfused at the microvascular level, even in the presence of complete left main coronary artery occlusion, whereas the right ventricular free wall was not perfused effectively at this level in any heart. Although there was considerable variation in the perfusion of the ventricular septum from heart to heart, the entire septum was not perfused in some of the hearts. We considered this poor perfusion of the septum to be due to the presence of well-developed thebesian veins in the septum. Retrograde coronary sinus perfusion of cardioplegic solution may be a valuable alternative to protect the left ventricular free wall, especially in cases of critical coronary artery stenosis or occlusion. However, antegrade perfusion should be used also, whenever possible, for adequate protection of the septum and the right ventricular free wall.     

Effect of an oxygen-enriched solution and multiple dosing of antegrade crystalloid cardioplegic solution on myocardial metabolism during coronary artery bypass graft operations.

The metabolic effect of excessive oxygenation and frequency of administration of antegrade crystalloid cardioplegic solution was assessed in 33 patients undergoing routine coronary artery bypass graft operations. Four patient groups were designed in which the initial aortic root injection was 1000 ml and then 100 ml administered through the vein grafts after completion of each distal anastomosis. The groups were divided as follows: group 1, single dose, normally oxygenated cardioplegic solution infused via the aortic root; group 2, single dose, high oxygen content cardioplegic solution infused via the aortic root; group 3, normally oxygenated cardioplegic solution with additional 250 ml doses via the aortic root every 20 minutes; group 4, high oxygen content cardioplegic solution with additional 250 ml doses via the aortic root every 20 minutes. In all groups myocardial mean septal temperature showed an immediate fall to approximately 11 degrees C with the initial aortic root doses and then a gradual rewarming to approximately 20 degrees C during the crossclamp period (mean 58.6 minutes). Metabolic parameters measured or calculated from the coronary sinus effluent were myocardial oxygen extraction, lactate production, base deficit, inorganic phosphate, glucose, potassium, creatine kinase (total and myocardial band fraction), and catecholamine production. There was no statistically significant difference in any of these determinations between each patient group. Furthermore, myocardial recovery, myocardial performance, and postoperative recovery characteristics were not different. We conclude that single or multidose aortic root crystalloid cardioplegic solution (either oxygen enriched or normally oxygenated) is equally effective in routine coronary artery bypass graft operations when septal temperatures are maintained between 15 degrees and 21 degrees C for a total arrest time of 60 minutes or less. In this study, increasing the volume cardioplegic solution given in multiple doses appeared to offer no significant metabolic or functional advantage in patients without complications who had satisfactory left ventricular function.     

Pressure monitoring of the coronary sinus during retrograde cardioplegia

Though the retrograde perfusion via the coronary sinus is a useful way of myocardial protection for more complicated cardiac surgery, coronary venous injury and inadequate preservation of the right ventricle were considered to be disadvantageous. In order to deal effectively with these problems we made a 3-way balloon catheter (Retro-Higami type 12 Fr) and evaluated the importance of monitoring the perfusion pressure in the coronary sinus in 214 patients. The mean perfusion pressure during retrograde cardioplegia infused by a pump was 29.4 +/- 9.1 mmHg, and had significant relation to the left ventricular mass weight (LVMW) which was calculated by UCG method. High perfusion pressure above 40 mmHg, which could have induced coronary venous injury, was noticed in 24 patients, but proper countermeasures could avoid venous injury completely. In 16 of those the high perfusion pressure was due to inadequate position of a tip of the catheter, and in other 8 it was due to relatively high flow rate of cardioplegic solution to LVMW. Twenty-eight patients showed low perfusion pressures below 20 mmHg, due mainly to the leakage from the orifice of the coronary sinus. The coronary sinus pressure during continuous gravity retroperfusion which was 9.2 +/- 2.6 mmHg seemed to bring optimal delivery of cardioplegic solution to the myocardium. On the basis of the results obtained from this clinical study we conclude that the monitoring of coronary sinus pressure during retroperfusion is useful not only to avoid coronary venous injury but to maintain adequate perfusion.     

Myocardial protection during aortic valve replacement. Selective infusion of cold cardioplegic solution into the left coronary artery

A simple method for hypothermic cardioplegia during aortic valve surgery is described. Cold cardioplegic solution (Ringer's acetate with 16 mEq potassium added) was selectively infused into the left coronary artery after the aorta had been opened. This resulted in an even cooling of the left ventricle with a relatively small amount of cardioplegic solution. Local cooling with "soft ice" was then initiated and the heart isolated from its warmer surroundings with the aid of a specially designed pad of compressed plastic foam. Thus, the left ventricular temperature could be kept below 20 degrees C for more than one hour. One hundred and three (103) patients were operated on with this method during a one-year-period. Only one patient died (1%). There were few early and/or late complications. Postoperative heart function was excellent in 23 patients subjected to a special study. Peak aortic pressure during the first 16 postoperative hours was 130 (+/- 22) mmHg, mean left atrial pressure 12 (+/- 2) mmHg, mean right atrial pressure 10 (+/- 2) mmHg and all patients were in sinus rhythm. There was a brief and limited release of myocardial enzymes postoperatively, indicating slight intra-operative myocardial damage. Apart from the cardioplegic technique, there are certain factors of importance for the efficacy of myocardial protection during aortic valve replacement. Among them may be mentioned avoidance of ventricular fibrillation, gentle reperfusion after release of the aortic cross-clamping, avoidance of left ventricular distension and administration of calcium intravenously before termination of bypass.     

Beating heart aortic valve replacement after previous coronary artery bypass surgery with a patent internal mammary artery graft

Re-sternotomy for aortic valve replacement (AVR) in patients with a patent internal mammary artery (IMA) graft may present a challenging surgical problem. Thus, strategies to prevent IMA graft injury include avoiding its dissection and leaving the graft open. However, when aortic cross clamping and cardioplegia are required, this approach may be associated with cardioplegia washout, suboptimal myocardial protection, and anterior myocardial wall injury. We herein describe an alternative technique for AVR on the beating heart in 4 patients with patent IMA grafts. The IMA was left unclamped and continuous retrograde coronary sinus perfusion (RCSP) was administered. Additional simultaneous antegrade venous bypass graft perfusion was established according to the extent of native coronary artery disease as well as patency and level of aortic proximal anastomoses. Using additional coronary ostia backflow control, the aortic valve was successfully replaced on the beating heart in all four cases without perivalvular leak. Postoperatively, low creatine kinase-MB fraction levels and preserved or improved ventricular function suggested very good myocardial protection. No myocardial infarction occurred in any patient. In our experience, aortic valve replacement on the beating heart using simultaneous antegrade-retrograde blood perfusion is a safe and effective method in this challenging subset of patients to prevent myocardial injury and to minimize the risk of patent IMA injury.